1. Field of Invention
The present invention relates to a centerless valve regrinder for valves used in an internal combustion engine. More particularly, this invention relates to a chuck for supporting the valve and rotating its face against a moving, abrading surface.
2. Description of the Related Art
A valve for an internal combustion engine consists essentially of a straight stem having a valve tulip on one end. The tulip has an upper surface that is substantially perpendicular to the axis of the stem and a fluted undersurface that joins with the stem. The undersurface has beveled face ground therein. The face mates with a seat in a head or block of the engine to form a seal. A valve is used for opening a piston cylinder, either to allow the input of fuel and oxygen to the cylinder or to allow the removal of exhaust. The valve is closed to form a seal to allow combustion of the fuel to power the engine. A valve becomes worn after it has been used in an engine for a period of time, and the mating between the valve face and seat forms less of a seal, thereby reducing the power of the engine. Rather than discard the valve, the valve face can be reground to improve the seal by means of a centerless valve regrinder.
The invention disclosed hereinafter is directed to solving certain longstanding problems that have escaped solution due to an apparent failure to understand certain important phenomena relating to centerless valve regrinders.
Consider the following passage from U.S. Pat. No. 2,567,320 ("CHRISTENSEN"):
Heretofore various types of valve facing devices have been used but have not been found entirely satisfactory for various reasons. Prior devices have been large and unwieldy as well as costly to manufacture. In addition, these prior devices have been difficult to adjust and operate and of complex construction. PA0 An object of the present invention is to provide a valve facing device of simple construction overcoming the drawbacks of previous devices. PA0 A further object is to provide a simplified construction of a portable facing device having adjusting means which are easily and quickly operable by experienced persons. PA0 Still another object is to provide a valve face of the character described which has accurate securing and holding means for a valve to be faced and which are quickly and easily placed into or out of operable position. PA0 Yet another object of the invention is to provide improved means for rotatably and angularly holding a valve for facing with a minimum of time and skill required for adjustment and operation thereof. PA0 In prior art devices for grinding valves and refacing valves elaborate chuck means ar provided and consequently such devices are costly. My invention, on the other hand, is of simple construction and of a cost that makes them available for use in small shops and garages. PA0 It is, therefore, an object of my invention to provide a simplified valve grinding machine wherein a valve may be ground quickly and accurately. PA0 It is another object of my invention to provide a simplified holding means for a valve to be ground which permits facile rotation and removal of said valve.
At Col. 1, lines 1-31.
Compare CHRISTENSEN, a 1950 patent, with U.S. Pat. No. 3,140,569 ("MURRAY"), a 1964 patent.
At Col. 1, lines 12-22.
Many patents in this field of technology mention increased simplicity and decreased cost as objects of the invention. Yet compare the ever increasing complexity of the prior art devices, e.g., CHRISTENSEN and MURRAY, and U.S. Pat. No. 4,428,160 ("WILLEMSEN"). Though the needs for increased simplicity and decreased cost have long been felt in the art, many developments in this field of technology accomplish the opposite.
Another interesting aspect of the prior art involves the use of a stop member for positioning the end of the valve stem that is opposite to the tulip part of the valve to limit the regrinding of the valve face. For example, MURRAY uses stop 54 and WILLEMSEN uses stop member 57 for this purpose. However, the invention disclosed hereinafter reflects the view that the use of this kind of stop member is a mistake and contrary to the above-identified objects.
A further interesting feature of the prior art involves the variety of chuck mechanisms used to hold and/or support the valve stem during the regrinding of the valve face. It is not unusual in the prior art to support the valve by means located only at or near the ends of the stem. With reference to U.S. Pat. No. 1,452,508 ("HERVIG"), one pair of wheels 33 is located adjacent to the tulip end of the valve stem and another pair of wheels 33 is located at the opposite end of the valve stem. WILLEMSEN shows a similar chuck mechanism with wheels 22 located at one end of the valve stem and a support means 37 with a V-shaped groove 41 spaced from the tulip end of the valve stem. The invention disclosed hereinafter reflects the view that this type of configuration is not optimal in terms of the above-identified objects of the invention and does not reflect an appreciation of certain phenomena relating to valve stem regrinding.